CAST (software)

CAST software is an environment which stems from an initial collaboration of Lorenzo Vigentini with the Laboratory for Cognitive Neuroscience and became a more extensive project in collaboration with Drs Brendan McGonigle and Margaret Chalmers (supported by a British Academy Grant) involving the implementation of a new software to support their research programme exploring human cognition and animal cognition.

Contents

Introduction

CAST is acronym for Computer Assisted Seriation Test. It is a software tool implemented to satisfy two major points:

the necessity of implementing a piece of software flexible enough to be accessed by non-programmers (usually psychologists);

the necessity of implementing a package powerful enough to provide a multimedia environment easy to expand.

The name comes with the idea of a metaphorical stage on which the instructor, or one who proposes/run the test, can define a scenario in which the elements can be organised and a set of exercises organised providing a completely flexible structure of the task for the testing.
The cast is the concept used to provide a structure to the list of elements that can be included in the setting.
These elements are the characters of the production, but also their behaviours on the stage. The ultimate idea is to provide an enjoyable experience for the subject tested and a powerful tool for monitoring the behaviour of the participant for the experimenter.

The software

The original concept was developed by Lorenzo Vigentini in 2001 and Paolo Vigentini initially programmed some of the core functionalities of the software.
The shell was developed using Macromedia Director, and two key metaphors represented the structural organization: the theatre and onion skin architecture. In this section, we present how these metaphors affected the design and summarize the key aspects of the software implementation in a research context.

The metaphor of the theatre

The theatre as a representation of the system came from the experimental paradigms. Elements of the experiments can be de-composed into a common set of building blocks that have a specific set of behaviors with a stable structure. This can be easily translated into the cast of characters and the props storage room. Macromedia Director was a good candidate for the development as it already supported a similar structure. Therefore we defined structural constructs namely Scenarios, Exercises, Tasks and Trials. These are nothing more than software classes, which resemble acts, scenes and dialogues of a play.

Scenarios are the containers holding all the necessary information about the configuration. In CAST, scenarios also refer to the actual configuration files, which are used to load a session. The various stage-scenes are represented in exercise-units related by the storyline of the scenario. These could be very distinctive for different tasks. The various acts of a play can then be transposed into the tasks and dialogues into trials. Adding or removing a property or behavior to the different units is easy because it allows us to extend the features of the unit itself. Programmers familiar with the OOP (object-oriented programming) model can certainly see the direct application of some basic principles; in addition, as the classes using this metaphorical reference are open, this allows for the conceptual inclusion of sketchy ideas not necessarily available in the original problem solution.

The onion skin architecture

Even if we have all these conceptually separate entities and functional units, the onionskin architecture is a good representation of the various organizational levels (layers) which determine how the program runs specific behavioral-units along the main program’s timeline.
In CAST provision of a relevant feedback is present at all the levels and units. Touches/trials/tasks/exercises have their own timeline, allowing a specific packaging of the tims-action unit with an introduction-presentation-response-feedback structure.

Applications

The CAST system has been used in a number of applications within Dr Chalmer's research programme investigating cognitive development and its derailment with autism, Fragile X syndrome and other pervasive developmental disorders. More information can be found in the publications list below.

References

McGonigle-Chalmers, M., Bodner, K., Fox-Pitt, A. and Nicholson, L. (2008), 'Size sequencing as a window on executive control in children with autism and Asperger's syndrome', Journal of Autism and Developmental Disorders, 38 (7), 1382-1390.